Libramarian
Adventurer
But too little symmetry is boring.
Why do we have to be stuck with humans, short humans, scrawny humans, and stout humans?
Can't a brother get a few big dumb lummoxes, horned crafty red people, and a sneaky green people?
Actually I agree with your assessment of demihumans as pretty much just short/scrawny/stout humans.
But my response is....then let's just have humans.

I don't much like other races actually. I'd be cool with ditching the race concept entirely. Unless they were really mechanically important, like race-as-class.
But I'm also kind of a pushover as a DM, so if somebody started a request with "can a brother..." I'd be like oh alright go for it.